i avoid fixed bias in tube amps that i sell, no back jobs.....
most of the amps i repair have fixed bias, i convert them to
cathode bias if and when the owner agreed...
where the owner agreed, he did not hear the difference between a fixed bias and a cathode bias...
most of the amps i repair have fixed bias, i convert them to
cathode bias if and when the owner agreed...
where the owner agreed, he did not hear the difference between a fixed bias and a cathode bias...
So?
How much difference does 2V make? From 20V to 22V? Not a lot.
If this will be a FULL POWER amplifier (such as to drive motors), then this IS the correct test for that application.
If this is to be a speech/music amplifier, you will hardly ever touch Full Power. Carefully rig your voltmeter so you can watch while you play music. In hi-fi use, the meter will hardly move. Yes, it may have a slightly different peak power with a low average. However in any sweet self-biased amp the difference is insignificant.
And of course Watts is just a number. The real test is whether it can play your sounds, on your speakers, in your room, at your levels, without getting harsh/nasty in the loud parts.
yes, we tested a 1000 watt ss amp and confirmed it by FTC sine wave,
but using speakers and using music, 100 watts of input power is already
painfull to the ears...
but using speakers and using music, 100 watts of input power is already
painfull to the ears...
Yeah... very good.
And it sure does all that ... in spades!
I am constantly amazed at the full realistic 3-D sound from this amp.
I have my Mp3 player loaded with my best music from the American song book Jazz and vocals from the 40s, 50s 60s .. the masters.. Ella Fitzgerald, Sarah Vaughan, Tony Bennett, Ben Webster on sax, .... etc etc.
I'm always amazed at sounds/notes that I never seem to have noticed before.
So, yes.. a lot of power is not as important as the quality it puts out.
This is the schematic:
http://pbpix.com/amp/6v6 pp amp change hw.png
IMHO those dangers have been greatly exaggerated. I have built and serviced quite a few valve amplifiers, both cathode and grid biased and see no major cause for concern, provided they're properly designed and set up.
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